International Journal of Marine Science, 2025, Vol.15, No.6, 320-328 http://www.aquapublisher.com/index.php/ijms 323 (CDOM) and suspended solids in the water are much higher, and the water clarity is also lower (Meirinawati et al., 2020). This is actually related to the feeding characteristics of sea cucumbers. They can process a large amount of POM and some gelatinous particles, reducing the absorption and scattering of light in water. However, it also depends on the density and the underlying environmental conditions. It's not the case that placing sea cucumbers will definitely be good. Figure 1 Sediment microbial load decreases in the presence of the sea cucumber Holothuria atra (Adopted from Maritan et al., 2025) 4.2 Nitrogen and phosphorus cycling and responses in primary productivity Sea cucumber farming not only helps to "clear the bottom", but also plays a significant role in the circulation of nutrients. They will absorb some inorganic nitrogen and phosphorus and also discharge them. This process promotes nutrient reuse to a certain extent and is also helpful for the primary production of the entire water body (Purcell et al., 2016). Especially in the IMTA system, "troublesome" indicators such as ammonia, nitrate and total phosphorus often decline significantly (Huo et al., 2024). Some farmers also add sodium bicarbonate as a carbon source to build a biofc system. As a result, the pH stabilizes, ammonia nitrogen decreases, and sea cucumbers grow well (Xiao et al., 2024). However, to improve these indicators, it really cannot rely solely on the sea cucumber species. Studies have found that when sea cucumbers are co-cultured with shrimp or even jellyfish, the removal rates of nitrogen and phosphorus are higher, but the prerequisite is that the quantities of each species are properly matched; otherwise, the effect will be reduced (Li et al., 2014; Chary et al., 2020). 4.3 Comparison of physicochemical parameters between cultured and non-cultured areas The same sea water can make a big difference whether sea cucumbers are raised or not. Many comparative studies in various places have shown that key indicators such as pH, dissolved oxygen, ammonia nitrogen and nitrate in aquaculture areas are more stable and closer to the ideal range. In waters without sea cucumbers, these data tend to fluctuate greatly, especially in the context of intensive aquaculture (Sadeghi-Nassaj et al., 2018; Zamora et al., 2018). In addition, sea cucumbers can also help reduce the number of bacteria in water bodies and improve water transparency, which is beneficial to the habitats of plankton and benthic animals. However, these effects are not equally significant everywhere (Liu and Han, 2025). It also depends on how the system structure is designed, what species are raised, and whether the daily management methods are in place.
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